The present invention is directed to an exercise device, specifically a progressive resistance exercise device.
One particular way to increase muscular strength is to provide a resistance to muscular movement during the course of an exercise. This type of strength training is generally referred to as resistance training and usually involves the repetitive raising or lowering of a load.
In the past, resistance training utilized free weights, such as barbells and dumbbells, which were handled by the exerciser during repetitive movements of a particular muscle or muscle group. While training with free weights provides an exerciser with the necessary resistance to muscular movement and thus provides the results sought by resistance training, there are many drawbacks in the use of free weights.
One disadvantage in using free weights is the inability to progressively increase or decrease the weight resistance during the course of an exercise. In general, the application of a progressively varying resistance during the course of a particular exercise, either in a response to the effort being applied by the exerciser or in response to a predetermined format for a particular exercise, has been found to beneficially improve muscle strength in comparison to traditional free weight training which does not provide such progressive resistance.
Another drawback with free weight training is the need to have another individual act as a spotter during the performance of an exercise, since the only support for the free weights is that support provided by the exerciser holding the weights. If the exerciser becomes tired or loses his grip of the free weights, the weights could fall onto the exerciser and result in serious injury.
Various types of machines have been devised which alleviate the need for spotters by supporting the weights independent of the exerciser. Some of these machines also provide a progressively varying resistance to the muscular movement during the course of an exercise.
One particular type of exercise device which independently supports numerous weights for use during an exercise is generally referred to as a weight-pulley machine. These weight pulley machines allow an exerciser to lift one or more numerous weights along a support post to which the weights are mounted. While these machines alleviate the danger of a falling weight, the exerciser can still be harmed as a result of the bar or lever to which the weights are coupled, typically by one or more cables, dropping back down on the exerciser.
Other types of devices completely dispense with the use of individual weights by utilizing instead, for example, an electrical motor or generator, or a hydraulically operated system to apply resistance to the movement of a bar or other suitable lifting mechanism. With these types of devices, the exerciser will exert a force, for example, upon a bar to move the bar along a predefined route or path, while a resistance is exerted to such pull by the operation of the electrical motor or generator. Examples of devices which utilize an electrical generator as the resistance applying mechanism are disclosed in U.S. Pat. Nos. 4,261,562 and 3,869,121.
Generally, with these types of devices a cable is wound about the rotatable axle of the electrical generator or motor. The individual grips and exerts a force to move a bar to which the cable is coupled while the electrical generator or motor is operated to resist the rotation of the axle. These types of devices typically utilize another mechanism for recoiling the cable about the axle and thus pull the bars in the opposite direction. For example, U.S. Pat. No. 4,261,562 discloses a power spring mechanism which recoils the cable onto the axle after the individual has uncoiled a portion of the wire.
These types of devices can still potentially injure the user if during the course of an exercise the exerciser loses a grip of the bar or fatigues. Since these devices exert a resistance to the movement of the bar in both directions, as does the previously discussed weight pulley machines, there still exists the possibility that the bar will snap back and injure the individual.
Still other types of devices are hydraulically powered, with a hydraulic piston reciprocally driving the bar as the exerciser performs various types of exercises. Devices of this type typically require extensive feedback control in order to provide the proper resistance to the exerciser's movement of the lifting mechanism. This feedback control monitors the amount of force applied by the exerciser during the course of moving the lifting mechanism. Examples of hydraulically powered exercising mechanisms are disclosed in U.S. Pat. Nos. 4,235,435 and 4,354,676.
A recent development in exercise devices is the use of a electromagnetic brake as the resistance applying mechanism. A particular benefit in using a magnetic brake is that the resistance can be applied in both directions, whereas electric motors or generators could only provide a resistance in one of the directions, with another mechanism required for applying a reverse resistance.
An example of an exercise device incorporating an electromagnetic brake is disclosed in U.S. Pat. No. 4,518,163. The disclosed device controls the resistance applied by the brake to the motion of a bar in both directions. Resistors, which control the flow of current to the brake, are connected to a series of transducers mounted along an arc following the path of travel for the bar. The transducers are activated sequentially by a wiper conductor mounted to the bar. These resistors vary the amount of current supplied to the electromagnetic brake and thus control the resistance applied by the brake to the bar as it is moved by the individual.
While this device advanced the art of exercising devices by the use of the electromagnetic brake, the device still suffers a disadvantage as a result of the manner by which the resistance is applied to the movement of the bar in both directions. This device varies the resistance applied by the electromagnetic brake in a step-like fashion as the wiper sequentially contacts each transducer and the voltage is abruptly increased by the then contacted resistor. This step-like increase in resistance potentially causes a jerking motion to the movement of the lifting mechanism during the course of an exercise.
There remains a need to provide an exercise device which substantially reduces the potential of injury to an exerciser by minimizing the possibility of the lifting mechanism snapping back upon the exerciser. Further, an exercise device is needed which supplies a gradual control of the resistance, while remaining simplified in construction and operation in order to limit maintenance requirements, particularly since many of these exercise devices are utilized in health club facilities where numerous individuals continuously work the devices.